Polyphenol is known as a representative of pigments and bitter-tasting components contained in fruits or plant seeds. This ingredient has been used in foods or cosmetics since a long time ago. In recent years, however, attention is increasingly focused on its health benefits (e.g., the suppressing effect of tea catechins on body fat), in large part because of the red wine boom incited by the so-called French paradox (Non-Patent Document 1). The amount of polyphenols contained in edible oil is small in the case of a refined oil such as salad oil, but on the other hand, this amount is relatively high in the case of a non-refined expressed oil such as olive oil or sesame oil. However, the existing oil expression technologies are problematic in that most of the polyphenols obtained by such technologies tend to stay behind as a residue in the by-product emerged after oil expression, without being obtained in the expressed oil (Non-Patent Document 2). To address this problem, there is known a method and apparatus for extracting useful components from a raw material by allowing a refined oil to be impregnated into the raw material and then subjecting to compression (Patent Document 1).
There are also other known methods designed to transfer useful components, such as flavor or antioxidant components, into an extracted oil by allowing an oil seed raw material or oil cake thereof to be mixed with a flavorless oil such as a refined oil. Examples of such methods include: a method which, as a means to extract useful components from plant bodies, includes transferring flavor or antioxidant components into a refined oil by allowing oil fruit/seed, cacao beans or rice bran to be mixed with a refined oil such as rapeseed oil, heat treatment, followed by oil separation (Patent Documents 2 and 3); a method which includes transferring flavor of a food material into a liquid oil such as a refined oil by allowing the food material to be pulverized in the liquid oil (Patent Document 4); and a method which includes producing a flavored oil by allowing oil seeds and spices to be expressed at the same time (Patent Document 5).    [Non-Patent Document 1] Shahidi F, Natural Antioxidant, Chemistry, Health Effects and Application, AOCS press, 1997    [Non-Patent Document 2] Artajo et al., J Sci Food Agric 86:518, 2006    [Patent Document 1] JP-A-2002-285188    [Patent Document 2] JP-A-05-146251    [Patent Document 3] JP-A-01-218549    [Patent Document 4] JP-A-2007-37470    [Patent Document 5] JP-A-2007-6851